<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Title</title>
  <style>
    body{margin: 0;overflow-y: scroll;}
    .gxContainer{width: 1400px;padding: 5px;margin: 0 auto;}
    .gxRow{margin-right: -5px;margin-left: -5px;}
    .gxCol4,.gxCol6{float: left;position: relative;}
    .gxCol4{width: 33.33333333%;}
    .gxCol6{width: 50%;}
    .gxCol4>div,.gxCol6>div{margin: 5px;background-color: wheat;height: 200px}
  </style>
</head>
<body>
<div class="gxContainer">

  <div class="gxRow">
    <div class="gxCol4"><div>1</div></div>
    <div class="gxCol4"><div>2</div></div>
    <div class="gxCol4"><div>3</div></div>
  </div>

  <div class="gxRow">
    <div class="gxCol6"><div>1</div></div>
    <div class="gxCol6"><div>2</div></div>
  </div>
  <div class="gxRow">
    <div class="gxCol6"><div>1</div></div>
    <div class="gxCol6"><div>2</div></div>
  </div>


</div>
</body>
</html>